There are just days left until Mozilla will release Firefox 4 Beta 7, the feature freeze release of Firefox 4.

This article has some interesting observations on performance, and other comments relavent to this thread.

Mozilla’s primary goal for Firefox 4 was improved performance. The idea was to increase the true rendering speed as well as the perception of browser speed.

Firefox 4 Beta 7 will integrate the new JavaScript engine JaegerMonkey, which takes the JavaScript performance of the browser into the neighborhood of IE9. Depending on your computer, you may see Firefox 4 either slightly faster or slower in the Sunspider test. We found Firefox 4 to respond much more favorably to multi-core systems than IE9. For example, Firefox 4 has a 5% lead over IE9 Beta on our Intel quad-core system and is about 10% behind on our AMD Athlon X2 test notebook at this time.

However, if you run Mozilla’s Kraken Benchmark, which claims to have more focus on real world apps, then you see Firefox ahead of every other browser out there. In the end, measuring JavaScript performance may be less important in the future as hardware acceleration becomes much more significant. There are a million and one ways out there how to measure JavaScript compilers today and it is somewhat up to you whom you believe.

Note that firefox 4 beta 7 is the first beta to integarte the new Jaegermonkey engine. This new engine provides a significant step up in performance, completely negating much of the observations made in this thread about earlier versions of firefox, and even earlier betas of Firefox 4.